This invention is in the field of imaging. In particular, the invention relates to X-ray imaging. And most particularly, the invention relates to a new process for obtaining ioversol.
This invention relates to N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-N-(2-hydroxyethyl)glycolamido-2,4,6-triiodoisopthalamide (ioversol).
Ioversol is commonly used as an X-ray contrast agent. The agent may be used in various radiographic procedures including those involving cardiography, coronary arteriography, aortography, cerebral and peripheral angiography, arthroglraphy, intravenous pyelography and urography as well as myelograpihy.
The present commercial manufacture of ioversol proceeds in four steps from bis(2,3-dihydroxypropyl)-2,4,6-triiodo-5-aminoisophthalamide to crude ioversol product, which product is subsequently purified. This conversion utilizes two expensive raw materials, acetoxyacetyl chloride (AAC) and bromoethylacetate (BEA), which together contribute to greater than 25% of the final product material cost. Additionally, the present commercial manufacturing process requires the use of several expensive, environmentally undesirable and/or reactive solvents such as 1,1,2-trichloroethane (TCE), dimethylsulfoxide (DMSO) and amylacetate. Each of these solvents have been particularly troublesome in manufacturing due to difficulties in recovery and other operational difficulties. TCE, in particular, is a chlorinated solvent of considerable concern in manufacturing. Thus, there exists a need for an improved process for then manufacture of ioversol which incorporates less expensive and more environmentally suitable raw materials.
The present invention provides a new process for producing ioversol (marketed in final dosage form as OPTIRAY(copyright)) comprising:
(a) reacting 5-amino-N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisopthalamide with chloroacetyl chloride in a polar aprotic solvent or combinations thereof to produce N,Nxe2x80x2-bis[2,3-di(2-chloroacetoxy)propyl]-5-(2-chloroacetamido)-2,4,6-triiodoisophthalamide;
(b) reacting the product of (a) with a base to produce N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-(2-chloroacetamido)-2,4,6-triiodoisopthalamide;
(c) reacting the product of (b) with an alkylating agent capable of producing a hydroxyethylated product in the presence of a base and water to produce N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-[N-(2-hydroxyethyl) (2-chloroacetamido)]-2,4,6-triiodoisopthalamide; and
(d) reacting the product of (c) in water and acetate ions to produce ioversol.
The new synthetic route replaces the high cost AAC and BEA components with chloroacetylchloride (CAC) and an alkylating agent which is capable of producing a hydroxyethylated product, respectively, thus reducing the introduction of these components to a more elementary and far less expensive archetype. Further, except for a small quantity of the polar aprotic solvent dimethylacetamide (DMAC) utilized in the initial step, the remaining reactions are conducted in an aqueous reaction medium, eliminating TCE, DMSO and amyl acetate and their corresponding costs and environmental difficulties.
The current process for producing ioversol is generally depicted in Table 1 below: 
The current general procedure for producing ioversol is as follows:
5-Amino-N,Nxe2x80x2-bis (2,3-dihydroxpropyl)-2,4,6-triiodoisophthalamide is dissolved in N,N-diomethylacetamide and acetylated with acetic anhydride, using 4-dimethylaminopyridine as a catalyst, to produce 5-amino-N,Nxe2x80x2-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalamide. Upon completion of the reactions the mixture is diluted with 1,1,2-trichloroethane and washed with aqueous sodium carbonate and aqueous sodium chloride solutions to remove acetic acid, which is the by-product of the reaction. The resulting 1,1,2-trichloroethane solution of the product is used in STEP #2.
Most of the solvent (1,1,2-trichloroethane) is distilled from the solution of 5-amino-N,Nxe2x80x2bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalamide prepared in STEP #1. The reaction solvent, N,N-dimethylacetamide, is added. Excess acetoxyacetyl chloride is added and the reaction mixture is stirred at ca. 40xc2x0 C. until the reaction is completed. 5-Acetoxyacetamido-N,Nxe2x80x2-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalamide is formed. 1,1,2-trichloroethane is added to dilute the reaction mixture and the solution is washed with aqueous sodium bicarbonate and aqueous sodium chloride solutions to remove acetoxyacetic acid and other by-products. The resulting organic layer which contains the reaction product is used in the next step.
Solvent (1,1,2-trichloroethane) is distilled from the solution of 5-acetoxyacetamido-N,Nxe2x80x2-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalamide prepared in STEP #2. Dimethyl sulfoxide is added as the reaction solvent. Potassium carbonate and 2-bromoethyl acetate are added and the mixture is stirred for ca. 10 hours at ca. 40xc2x0 C. to complete the reaction to form 5-[N-(2-acetoxyethyl)acetoxyacetamido]-N,Nxe2x80x2-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalamide. After the reaction is completed, 1,1,2-trichloroethane is added to dilute the mixture. To remove the inorganic salts and dimethyl sulfoxide in the medium, the mixture is washed once with deionized water, and twice with aqueous sodium chloride solution. The organic layer, which contains the product, is then distilled to remove the solvent and the residue is dissolved in amyl acetate while the mixture is still hot. The mixture is then cooled and stirred continuously to complete the crystallization. The reaction product is collected and dried. After testing, it is used in STEP #4 to prepare crude ioversol aqueous solution.
5-[N-(2-Acetoxyethyl)acetoxyacetamido]-N,Nxe2x80x2bis(2,3-diacetoxypropy)-2,4,6-triiodoisophthalamide solids are slurried in hot water containing a catalytic quantity of sulfuric acid. The solid gradually dissolves as it is heated with the steam on the jacket. The material is hydrolyzed to produce crude ioversol and acetic acid as a by-product. To remove the acetic acid, clean steam is sparged into the reactor. The solution volume is maintained constant by adding deionized water during the reaction and acetic acid removal. The reaction is tested for completeness of hydrolysis and for the removal of acetic acid.
The solution which contains ioversol, (crude ioversol aqueous solution) is cooled and utilized in subsequent purification steps.
The process of the invention for producing ioversol is depicted in Table 2 below: 
The general procedure for the process of the invention involves reacting 5-amino-N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide with chloroacetyl chloride in a polar aprotic solvent.
The general procedure for the process of the invention involves reacting 5-amino-N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide with N,N-dimethylacetamide and chloroacetyl chloride. The resulting product is hydrolyzed with a base (such as sodium hydroxide). A homogeneous solution is obtained by adding water. Precipitation is affected to yield N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-(2-chloroacetamido)-2,4,6-triiodoisophthalamide. Alternately, 5-amino-N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide is reacted with N,N-dimethylacetamide, acetonitrile, and chloroacetyl chloride. The resulting product is hydrolyzed with a base. A homogeneous solution is obtained by adding water. Precipitation is affected to yield N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-(2-chloroacetamido)-2,4,6-triiodoisophthalamide. This product is combined with an aqueous base and deionized water. 2-Chloroethanol is added followed by heating. The addition of hydrochloric acid yields N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-[N-(2-hydroxyethyl)(2-chloroacetamido)]-2,4,6-triiodoisophthalamide. Alternately, N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-(2-chloroacetamido)-2,4,6-triiodoisophthalamide plus metal halide and deionized water are combined. Ethylene oxide is added followed by heating. The addition of hydrochloric acid yields N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-[N-(2-hydroxyethyl)(2-chloroacetamido)]-2,4,6-triiodoisophthalamide. This product is suspended in water with acetate ions and hydrochloric acid added. This suspended solution can take place at or above atmospheric pressure. Generally about 1 to about 2 atmospheres above atmospheric pressure is used. After adding aqueous sodium hydroxide to, maintain the pH, the reaction yields N,Nxe2x80x2-bis(2,3-dihydroxypropyl)-5-N-(2-hydroxyethyl)glycolamido-2,4,6-triiodoisopthalamide. Finally, salts and low molecular weight impurities are removed.
Polar aprotic solvents for use with the invention include dimethylacetamide, acetonitrile, dimethylsulfoxide, dimethylformamide, tetrahydrofuran, dimethoxyethane, dioxane, or combinations thereof. Suitable bases for use with the water include sodium hydroxide, lithium hydroxide, ammonium hydroxide, potassium hydroxide, disodiumhydrogenphosphate, trisodiumphosphate, dipotassiumhydrogenphosphate, tripotassiumphosphate, dilithiumhydrogenphosphate, trilithiumphosphate, diammoniumhydrogenphosphate, and triammoniumphosphate. Alkylating agents capable of producing a hydroxyethylated product suitable for use with the invention include 2-chloroethanol, ethylene oxide, ethylene carbonate, 2-bromoethanol, 2-iodoethanol, and 2-tosylethanol. Acetate ions for use with inventions include sodium, lithium, ammonium and potassium.
Specifically, the process of the invention is detailed in the Examples section of this document.
The following examples illustrate the specific embodiments of the invention described in this document. As would be apparent to skilled artisans, various changes and modifications are possible and are contemplated within the scope of the invention described.